1. Field of the Invention
The present invention relates generally to sealing and fastening systems for panels, and more particularly to a sealing and fastening system for panels which form substantially the entire outside wall area of a greenhouse.
2. Description of Related Art
Generally, greenhouses are formed to the traditional quonset design as illustrated in FIG. 1. These type of greenhouses have a supporting frame structure which is covered with large panels made from a transparent material Typically, the supporting frame structure includes a plurality of longitudinally spaced and generally arcuate tubular members known as "hoops". The supporting frame structure also includes a plurality of transversely spaced and longitudinally extending tubular members known as "purlins". The purlins are secured to the hoops on either the interior or exterior surface thereof. The panels are secured to either the hoops or purlins. The panels are made of a transparent and impact resistant polycarbonate material such as LEXAN.RTM. sold by the General Electric Company. Typically, these panels have an inner and outer wall spaced by a plurality of longitudinally extending interior walls which are generally perpendicular to the inner and outer walls.
In the past, the panels were connected to the hoops or purlins by a fastening system which used a two-piece aluminum extrusion and fasteners such as screws. Typically, the aluminum extrusion was fastened to either the hoops or purlins and sheet metal screws are driven into the outer wall of two adjoining panels to secure the panels to the aluminum extrusion.
One disadvantage of the above fastening system is that assembly and disassembly of the panels to the supporting structure is slow. Another disadvantage of the above fastening system is that it is complex and costly to manufacture and install. Yet another disadvantage is that the screws put apertures or holes into the panels. This may result in water leaks around the screws when it rains.